Environmental activists sailed four ships into a test zone and hounded a nuclear submarine Friday in a tense game of cat-and-mouse on the high seas, successfully forcing the Navy to delay a Trident 2 missile launch, the Navy said. "The planned Trident 2 D-5 test missile launch was terminated today because of intentional interference from foreign-flagged ships in a designated hazardous operation area," a written statement from the Navy said.

An "incorrect system setting" caused the shutdown of two interceptor missile launches in a failed test Thursday of the sea-based U.S. missile defense system, the military announced. One dummy enemy ballistic missile was launched from the Pacific Missile Range Facility on Kauai, Hawaii, simulating a missile attack on U.S. territory, and the second shorter-range missile was launched from a Navy aircraft and aimed at the anti-missile ship intended to stop the attack, the U.S.

The Defense Department's seventh test of Lockheed Martin Corp.'s troubled missile-interceptor system was postponed Tuesday because of problems with the surrogate enemy missile, the Pentagon said. The test was to have occurred at White Sands Missile Range in New Mexico Tuesday morning. No date was set for another try, an official said. The Theater High Altitude Area Defense system, or THAAD, interceptor missile failed in a test in late March, flying past its target.

A top Pentagon official is casting new doubt on the progress of the government's leading missile-defense technology, saying two recent test-flight successes haven't established how well the controversial system could handle an actual attack. The test flights, carried out after six consecutive failures, have been hailed by advocates as evidence that the Army's $15.4-billion Theater High Altitude Area Defense (THAAD) system will be able to protect troops on the battlefield from missile attacks.

Just two months after signing an accord with the United States designed to prevent dangerous military activities, the Soviet Union is planning to test missiles on flight paths that would pass over Hawaii, U.S. officials said Friday. The United States lodged two protests this week over the proposed test flights of unarmed missiles, warning that such moves would be provocative and could endanger the safety of the islands in the event of the missiles' failure.

Military officials postponed a planned missile defense test because of bad weather over Vandenberg Air Force Base in California. A dummy warhead was set to be launched over the Pacific Ocean to be intercepted by a rocket. Pentagon officials said an attempt would be made tonight. The test is part of the Bush administration's plan to develop a system that can shoot down an enemy's intercontinental missiles before they reach U.S. soil.

Iran on Saturday dismissed allegations that it was providing test sites for North Korean long-range missiles designed to deliver nuclear warheads, its official Islamic Republic News Agency reported. A Bush administration official said last week that North Korea was getting around a self-imposed missile test ban by sharing technology information with Iran, which is allegedly carrying out missile tests on Pyongyang's behalf.

With border tensions between South Asia's nuclear neighbors running high, Pakistan test-fired a new surface-to-surface missile today, its state-run news agency said. India was given prior warning of the test, according to Associated Press of Pakistan. The missile is one in a series of medium-range missiles developed for Pakistan's arsenal.

Pakistan successfully test-fired a locally developed cruise missile that can carry a nuclear warhead and hit targets within a 310-mile range, the army said in a statement. The test at an undisclosed location in Pakistan was the second involving the Hatf VII cruise missile, also known as the Babur, the statement said. The previous firing was conducted in August on the 62nd birthday of President Pervez Musharraf.